"We are so grateful to share that Maddie is making progress," Spears posted to Twitter. "Thank you all for sending thoughts and prayers our way. Let's all keep praying."
Maddie is the daughter of Britney Spears' younger sister Jamie Lynn Spears. On Sunday, she was hospitalized in critical but stable condition following an accident on their family's Louisiana property where she was trapped underwater in a pond while strapped into the ATV. Jamie Lynn Spears and her husband, Jamie Watson, were watching as it happened.